title: Synthesis and characterization of a glycerol salicylate resin for bioactive root canal sealers.
abstract: OBJECTIVE
  To develop and characterize a salicylate resin with potential use in bioactive endodontic sealers.
  
  
  METHODS
  Methyl salicylate, glycerol and titanium isopropoxide were added in a closed system for the transesterification reaction. The resin obtained was characterized by proton nuclear magnetic resonance spectroscopy (1H NMR) and size exclusion chromatography (SEC). To verify the applicability of the resin to the development of endodontic sealers, experimental cements were prepared by mixing glycerol salicylate resin, calcium hydroxide and methyl salicylate in the ratios of 2 : 1 : 1, 1 : 2 : 1, 1 : 1 : 2, 1 : 1 : 1, 4 : 1 : 1, 1 : 4 : 1 and 1 : 1 : 4. Setting times were measured according to ISO 6876. Features of the hardening reaction were described by micro-RAMAN spectroscopy.
  
  
  RESULTS
  The transesterification reaction had a 72% efficiency. The (1) H NMR analysis revealed the presence of the expected functional groups (hydroxyls and aromatic rings), and the SEC confirmed the molar mass of the resin produced. The setting times of experimental sealers ranged from 70 min (ratio 1 : 1 : 1) to 490 min (ratio 1 : 1 : 4). The conversion of the salicylic groups (1 613 cm(-1) ) to salicylate salt (1 543 cm(-1) ) and the reduction in calcium hydroxide peaks (1084 and 682 cm(-1) ) were confirmed by micro-RAMAN spectroscopy, which showed the calcium chelation by the resin.
  
  
  CONCLUSIONS
  The new glycerol salicylate resin was successfully synthesized and revealed a potential application in the development of endodontic sealers.
authors.affiliation: Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: F F
authors.initials: FF
authors.lastname: Portella
authors.forename: P D
authors.initials: PD
authors.lastname: Santos
authors.forename: G B
authors.initials: GB
authors.lastname: Lima
authors.forename: V C B
authors.initials: VC
authors.lastname: Leitune
authors.forename: C L
authors.initials: CL
authors.lastname: Petzhold
authors.forename: F M
authors.initials: FM
authors.lastname: Collares
authors.forename: S M W
authors.initials: SM
authors.lastname: Samuel
mesh_terms: D002126:Calcium Hydroxide / Q000737:chemistry; D005990:Glycerol / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D009942:Organometallic Compounds / Q000737:chemistry*; D019279:Resin Cements / Q000138:chemical synthesis*; D012387:Root Canal Filling Materials / Q000138:chemical synthesis*; D012459:Salicylates / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D019279:Resin Cements; D012387:Root Canal Filling Materials; D012459:Salicylates; C102815:titanium isopropoxide; C033069:methyl salicylate; D005990:Glycerol; D002126:Calcium Hydroxide
keywords: RAMAN; bioactive sealers; glycerol; salicylate; salicylate resin